1. Field of the Invention
The present invention relates to a wet-type electrophotographic image forming apparatus. More particularly, the present invention relates to a method for controlling an oxidation catalyst device for a wet-type electrophotographic image forming apparatus for improving the oxidation resolution efficiency of carrier vapors produced when a paper deposited with a developer passes through a fixation device.
2. Description of the Related Art
In general, a wet-type electrophotographic image forming apparatus scans a laser beam on a photosensitive medium to form an electrostatic latent image, deposits a developer on the electrostatic latent image, thereby forming a visible image, and transfers the visible image onto a predetermined paper. Thus, a desired image is printed out. The wet-type electrophotographic image forming apparatus is preferred in color printing because it can produce a more distinct image as compared to a dry-type electrophotographic image forming apparatus that uses powder toner.
FIG. 1 shows a construction of a conventional wet-type electrophotographic image forming apparatus.
As shown in FIG. 1, the conventional wet-type electrophotographic image forming apparatus 100 comprises an image forming apparatus body 110, a plurality of photosensitive drums 121, 122, 123, and 124, a plurality of charging devices 131, 132, 133, and 134 for charging the respective photosensitive drums 121, 122, 123, and 124 to a predetermined potential. Apparatus 100 further comprises a plurality of exposure devices 141, 142, 143, and 144 for scanning a laser beam onto the respective electrified photosensitive drums 121, 122, 123, and 124; a plurality of developing devices 151, 152, 153, and 154 for supplying developers to the respective photosensitive drums 121, 122, 123, and 124 to form a visible image; and a plurality of first transfer rollers 171, 172, 173, and 174 for transferring the visible images formed on the respective photosensitive drums 121, 122, 123, and 124 onto a transfer belt 160. In addition, apparatus 100 comprises a second transfer roller 180 for transferring a resultant image formed on the transfer belt 160 from overlapped visible images to a paper P, and a fixation device 190 for applying heat and pressure to a paper P with the transferred resultant image, thereby fixing the resultant image on the paper P.
The plurality of developing devices 151, 152, 153, and 154 store developers of different colors, respectively, and each of the developing devices supplies a color developer to one of the plurality photosensitive drums 121, 122, 123, and 124. The developers consist of an ink and liquid carrier such as Norpar. Norpar is a hydrocarbon-based solvent, which is a mixture of C10H22, C11H24, C12H26, and C13H28. Developers deposited on the respective photosensitive drums 121, 122, 123, and 124 to form visible images are transferred to the transfer belt 160 and are overlapped with each other. A resultant image is formed from the overlapped visible images on the transfer belt 160. The resultant image is then transferred to paper P forming the desired image. The paper P then passes through the fixation device 190, where the ink component in the developers is fixed on the paper and the liquid carrier is vaporized by high temperature and discharged outwardly in the form of a combustible hydrocarbon gas, such as CH4.
The combustible hydrocarbon gas is a volatile organic compound, which can contaminate the environment and emits an offensive odor when discharged.
Methods for removing combustible hydrocarbon gases known in the art include a filtration method for physically removing gaseous components using a carbon filter such as active carbon, a direct combustion method for combusting gaseous components at an ignition point (600° C. to 800° C.), and a catalytic oxidation method for combusting gaseous components at a relatively lower temperature (150° C. to 400° C.) using a catalyst, thereby oxidizing and resolving the components into water and carbon dioxide.
In the filtration method, the carbon filter does not have a capability of resolving the entrained carrier vapors. Therefore, a carbon filter saturated with carrier vapors needs to be replaced frequently when the amount of entrained carrier vapors exceeds a predetermined amount. The direct combustion method is potentially unsafe.
Due to the above described problems, wet-type electrophotographic image forming apparatuses have mainly employed the catalytic oxidation method for removing carrier vapors. In addition, various advancements have been made for increasing the efficiency of oxidizing and resolving carrier vapors.